Luke Shaw will become the world’s most expensive teenager when his £31.5million move to Manchester United is confirmed.

Others who have worn the tag include the Brazilian Ronaldo (twice), former Swansea City boss Michael Laudrup and current holder Wayne Rooney, a soon-to-be team-mate of Shaw.

Boy wonders: Luke Shaw will top the list of most expensive teenagers when he signs for Manchester United

All smiles: Luke Shaw's £31.5m move to Manchester United will make him the world's most expensive teenager

VIDEO Luke Shaw signs for Manchester United

Be warned, though, for every Ronaldo there is a Caio. Remember him? Caio Ribeiro Decoussau, then 19, signed for Inter Milan from Sao Paulo for £6.6m in 1995 but made just six Serie A appearances for the Nerazzurri.

Here, Sportsmail takes a look at the 10 most expensive teenagers in history and determines whether they were a hit, a miss or a maybe.

MOST EXPENSIVE TEENAGERS IN WORLD FOOTBALL SINCE 1980

June, 1980:Clive Allen (19) QPR to Arsenal - £1.25m

June, 1983: Michael Laudrup (18) Brondby to Juventus - £1.3m

July, 1991:Dino Baggio (19) Torino to Juventus - £4.4m

July, 1994:Ronaldo (17) Cruzeiro to PSV - £4.8m

July, 1995:Caio (19) Sao Paulo to Inter - £6.6m

July, 1996:Ronaldo (19) PSV to Barcelona - £13m

January, 2001:Antonio Cassano (19) Bari to Roma - £18m

August, 2004:Wayne Rooney (18) Everton to Man Utd - £25.6m

10) June, 2006: John Obi Mikel (19) Lyn Oslo to Chelsea - £16m

MAYBE – Still splits opinion at Stamford Bridge given the hype amid the prolonged struggle to prise him from the grasp of Manchester United. What you cannot argue with is his return of four FA Cups, a Premier League and Champions League title.

HIT – He enjoyed five goal-laden years with Atletico – bulging the net on 101 occasions – and fired them to Europa League glory in 1010 before a handsome profit was returned on his £38m move to Manchester City.

8) August, 2007: Alex Pato (17) Internacional to Milan - £17m

MISS – The Brazilian’s initial promise ultimately faded and, having returned double figures in three consecutive seasons between 2009 and 2011, injuries perhaps mitigated his decline and he signed for Corinthians in January of last year for £12m.

Blue order: John Obi Mikel signed for Chelsea for £16m in 2006

Unveiling: Sergio Aguero and Atletico Madrid president Enrique Cerezo Torres during his official presentation at the Vicente Calderon

Guard of honour: Alexandre Pato is escored by Italian police ahead of his move to AC Milan

7) August, 2011: Romelu Lukaku (18) Anderlecht to Chelsea - £17m

MAYBE – West Brom and Everton fans would argue otherwise, but from a Chelsea perspective Lukaku is yet to prove his worth and it remains to be seen whether he will ever get the chance to do so.

New boy: Romeulu Lukaku was just 18 when he signed for Chelsea, then under the charge of Andre Vilas-Boas

MISS – Five tumultuous seasons – defined by fallouts with every coach, including Fabio Capello – were brought to a close when he signed for Real Madrid for just £4m in 2006. His talent was never in doubt, but as for his temperament…

Trouble ahead: Antonio Cassano was the world's most expensive teenager at £18m when he signed for Roma in 2001

5) May, 2007: Anderson (19) Porto to Man Utd - £18m

MISS – Perhaps the most resounding failure to reside on this list is the Brazilian midfielder, who has drifted to near obscurity at Old Trafford and ended last season on loan at Fiorentina.

Flop: Sir Alex Ferguson expected more of Anderson when he joined for £18m in 2007

4) July, 2005: Sergio Ramos (19) Sevilla to Real Madrid - £21m

HIT – Much was made of his mega-money move to the Bernabeu but Ramos has been worth every cent. He has now made more than 400 appearances for Los Blancos and scored the all-important equaliser in the Champions League final victory over city rivals Atletico in May.

Thumbs up: Sergio Ramos has proved a success at Real Madrid

3) July, 2013: Marquinhos (19) Roma to PSG - £23.5m

MAYBE – Still just 20 years old, the Brazilian centre-back enjoyed an impressive first season in Paris and has broken into the Brazil senior side.

One for the future: PSG centre-back enjoyed an impressive first season in Ligue 1

2) July, 2001: Javier Saviola (19) River Plate to Barcelona - £24m

MISS – That two of his six seasons at the Nou Camp were spent on loan elsewhere serves to highlight his struggle – this despite early promise – and he left for Real Madrid on a free transfer having scored just 49 La Liga goals.

Not so handy: Javier Saviola's Barcelona career eventually faded to disappointment

1) August, 2004: Wayne Rooney (18) Everton to Man Utd - £25.6m

HIT – A debut hat-trick against Fenerbahce set the tone for Rooney’s early years at Old Trafford and he has since returned double figures in each of his 10 seasons. He perhaps peaked with 34 goals in 2012 but he remains a key player and will be hoping the arrival of Louis van Gaal can spark a revival in his fortunes.

Gr-eight: Wayne Rooney became the world's most expensive teenager following his £25.6m move to Old Trafford